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Effect of okadaic acid, a protein phosphatase inhibitor on heat stress-induced HSP72 synthesis and thermotolerance

Joyeux, M; Arnaud, C; Richard, MJ; Yellon, DM; Demenge, P; Ribuot, C; (2000) Effect of okadaic acid, a protein phosphatase inhibitor on heat stress-induced HSP72 synthesis and thermotolerance. CARDIOVASC DRUG THER , 14 (4) 441 - 446.

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Abstract

Heat stress proteins (HSPs), in particular HSP72, seem to play a major role in cell protection against lethal stresses such as hyperthermia or ischemia. HSP synthesis is negatively regulated by protein phosphatases, which are implicated in dephosphorylation processes. In the present study, we have investigated the effect of okadaic acid (OA, a protein phosphatase inhibitor) on heat stress-induced HSP72 synthesis and thermotolerance in smooth muscle cells (SMC).SMC were heat stressed (42 degrees C for 20 minutes) in the presence of 250 nM OA (HS+OA cells) or its vehicle (HS+V cells). Control (OA or V) cells were not heat stressed. HSP72 mRNA expression was determined 1, 1.5, 3, and 6 hours after heat stress by RT-PCR, and HSP72 synthesis was determined 6, 12, 24, 48, and 72 hours after heat stress by Western blotting. SMC survival of lethal hyperthermia (47 degrees C for 90 minutes) was assessed 6, 24, and 48 hours after heat stress by a tetrazolium assay.The maximal expression of HSP72 mRNA was markedly prolonged in HS+OA cells (until 6 hours after heat stress) compared to HS+V cells (1 hour after heat stress). The kinetics of HSP72 synthesis and thermotolerance of SMC were not different between HS+OA and HS+V cells. Baseline HSP72 mRNA and protein expression were similar in control Vend OA cells.In conclusion, okadaic acid treatment of SMC potentiated HSP72 mRNA expression without affecting heat stress-induced HSP72 synthesis and thermotolerance.

Type:Article
Title:Effect of okadaic acid, a protein phosphatase inhibitor on heat stress-induced HSP72 synthesis and thermotolerance
Keywords:heat stress, heat stress protein, okadaic acid, protein phosphatases, smooth muscle cells, TRANSGENIC MICE, SHOCK PROTEIN, RAT, CELLS, EXPRESSION, PHOSPHORYLATION, OVEREXPRESSION, PROTECTION, HSP-70, INJURY
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Population Health Sciences > Institute of Cardiovascular Science

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